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SubjectRe: [PATCH] scsi: ufs: Don't disable core_clk_unipro if the link is active
Hi Stanley,

On 2020-11-24 13:20, Stanley Chu wrote:
> Hi Can,
>
> On Mon, 2020-11-23 at 21:05 -0800, Can Guo wrote:
>> If we want to disable clocks but still keep the link active, both
>> ref_clk
>> and core_clk_unipro should be skipped.
>>
>
> "core_clk_unipro" seems used by ufs-qcom only and not defined in the
> UFS
> platform binding document: ufshcd_pltfrm.txt.

Agree.

>
> Could you please add the definition first and then it would be
> reasonable to be used in common driver?
>
> Or, how about add a flag in struct ufs_clk_info indicating if this
> clock
> needs be ON to keep the link active? The flag could be set properly by
> vendor initialization functions. In this way, we can also remove the
> hard-coded "ref_clk" in __ufshcd_setup_clocks().

This seems better, I will upload next version to incorporate the idea
after it is tested.

Thanks,

Can Guo.

>
> Thanks.
> Stanley Chu
>
>> Signed-off-by: Can Guo <cang@codeaurora.org>
>>
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
>> index a7857f6..69c2e91 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -222,7 +222,7 @@ static int ufshcd_clear_tm_cmd(struct ufs_hba
>> *hba, int tag);
>> static void ufshcd_hba_exit(struct ufs_hba *hba);
>> static int ufshcd_probe_hba(struct ufs_hba *hba, bool async);
>> static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on,
>> - bool skip_ref_clk);
>> + bool keep_link_active);
>> static int ufshcd_setup_clocks(struct ufs_hba *hba, bool on);
>> static int ufshcd_uic_hibern8_enter(struct ufs_hba *hba);
>> static inline void ufshcd_add_delay_before_dme_cmd(struct ufs_hba
>> *hba);
>> @@ -1710,7 +1710,6 @@ static void ufshcd_gate_work(struct work_struct
>> *work)
>> if (!ufshcd_is_link_active(hba))
>> ufshcd_setup_clocks(hba, false);
>> else
>> - /* If link is active, device ref_clk can't be switched off */
>> __ufshcd_setup_clocks(hba, false, true);
>>
>> /*
>> @@ -7991,7 +7990,7 @@ static int ufshcd_init_hba_vreg(struct ufs_hba
>> *hba)
>> }
>>
>> static int __ufshcd_setup_clocks(struct ufs_hba *hba, bool on,
>> - bool skip_ref_clk)
>> + bool keep_link_active)
>> {
>> int ret = 0;
>> struct ufs_clk_info *clki;
>> @@ -8009,7 +8008,13 @@ static int __ufshcd_setup_clocks(struct ufs_hba
>> *hba, bool on,
>>
>> list_for_each_entry(clki, head, list) {
>> if (!IS_ERR_OR_NULL(clki->clk)) {
>> - if (skip_ref_clk && !strcmp(clki->name, "ref_clk"))
>> + /*
>> + * To keep link active, ref_clk and core_clk_unipro
>> + * should be kept ON.
>> + */
>> + if (keep_link_active &&
>> + (!strcmp(clki->name, "ref_clk") ||
>> + !strcmp(clki->name, "core_clk_unipro")))
>> continue;
>>
>> clk_state_changed = on ^ clki->enabled;
>> @@ -8580,7 +8585,6 @@ static int ufshcd_suspend(struct ufs_hba *hba,
>> enum ufs_pm_op pm_op)
>> if (!ufshcd_is_link_active(hba))
>> ufshcd_setup_clocks(hba, false);
>> else
>> - /* If link is active, device ref_clk can't be switched off */
>> __ufshcd_setup_clocks(hba, false, true);
>>
>> if (ufshcd_is_clkgating_allowed(hba)) {

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